These files provide a collection of chemical structures for validating Cahn-Ingold-Prelog (CIP) descriptor labelling implementations.

Please Cite:

Robert M. Hanson, John W. Mayfield, Mikko J. Vainio, Andrey Yerin, Sophia Musacchio, and Dmitry Redkin. Algorithmic analysis of Cahn-Ingold-Prelog rules of stereochemistry: Proposals for revised rules anda guide for machine implementation (Under Preparation)

Each entry provides a set of recommended labels agreed upon by the authors of the above manuscript. Beyond the corner cases addressed in the manuscript these labels can be considered to match the IUPAC recommendations. Please notify us if you believe an assignment is incorrect.

Each label is described as an atom number and a CIP descriptor label:

<atom_num><label>

A descriptor label is one of the following:

R, S, r, s, M, P, m, p, Z, or E	

Atom numbers start at 1 and reference the explicit atom storage order of the input format. Explicit hydrogens are counted in this numbering but hydrogens specified as an atom property '[C@H]' are not. For example in SMILES (R)-butan-2-ol could be labelled as:

C[C@H](CC)O 2R
CC[C@H](C)O 3R
C[CH2][C@H](C)O 3R
CC([H])([H])[C@H](C)O 5R

When a stereo unit spans multiple atoms two and only the two 'end' atoms are labelled.

C/C=C/C 2E 3E
CC=[C@]=CC 2M 4M

T

Each entry lists the CIP stereo unit found.

For Extended Tetrahedral and CisTrans the <num> indicates the number of atoms in the cumulated chain. For example penta-2,3-diene is TH3, hexa-2,3,4-triene is CT4.

Note Helicicene and Atropisomeric stereochemistry can not be stored in SMILES.

Each entry contains the set of the CIP sequence rules required to get the recommended answer.

'1a,2,5' Requires Rule 1a, 2, and 5.

• v1.0 2018-05-20, Initial public release